The information provided here should serve to indicate which are the most important factors to be considered when selecting a standard "bearings types" and thus facilitate an appropriate choice.

So, with ball bearings you also have different types of ball bearings. You'll notice here, this bearing is quite small. It's a little bit thinner and on the axle itself compared to this one, you can see the diameter over itself is pretty small. So there's different sizes. Sometimes the larger they are, the easier it is to keep them spinning longer 'cause they make a wider gap, it won't grab the string quite as fast and you'll really get some good spin time out of it. When it comes down to it though, small versus large bearing, it doesn't make the hugest difference in the world, I won't freak out if you have a small bearing yo-yo and I don't think that you need a large bearing yo-yo for things to work. The next step from a regular bearing is something called a concave bearing.

And if you zoom-in on this bearing, you can actually see it's got a little groove in it if you compare it to this one. Because of that little groove, the string can actually sit right down into that skf bearing and what that allows you to do is it allows the string to sit there and it won't get caught by the edge of the yo-yo quite as well and it also centers it so when you're doing tricks on the string, the yo-yo moves to one side or the other. It's not going to as quickly grab the edge of the yo-yo. It's going to be centered there. It allows you to do tricks at much longer time, allows everything to keep smooth and what not. 

In bearings of this type, the cylindrical rollers are in linear contact with the raceways. They have a high radial load capacity and are suitable for high speeds.

There are different types designated as NU, NJ, NUP, N, NF (for single-row bearings), NNU, and NN (for double-row bearings depending on the design or absence of side ribs).

The outer and inner rings of all types are separable.

Some cylindrical roller bearings have no ribs on either the inner or outer ring, so the rings can move axially relative to each other. These can be used as free-end iko bearings. Cylindrical roller bearings, in which either the inner or outer rings has two ribs and the other ring has one, are capable of taking some axial load in one direction Double-row cylindrical roller bearings have high radial rigidity and are used primarily for precision machine tools.

SN532

SN609

SN610